The Doppler inertial acoustic system for littoral navigation (DIAS)

The Doppler inertial acoustic system (DIAS) is a compact, low-power, inertially-aided Doppler velocity navigation system which was developed to enhance the navigation capabilities of an unmanned underwater vehicle (UUV) in search, reacquisition, and inspection applications. Based on experience gained in the employment of long-baseline acoustic navigation approach using the divers acoustic navigation system (DANS) in support of the explosive ordnance disposal remote work packages program (EODRWP), DIAS provides for navigation of small subsea vehicles operating in shallow water without requiring reliance on external reference points reducing operational complexity. The primary navigation components in DIAS include a recently developed high-frequency (1200 kHz) Doppler velocity log and a relatively low-cost, low-power, miniature solid-state inertial package. Sensor data collection, prefiltering and integration is accomplished using a low-power digital signal processor (DSP) based single board computer (SBC) resulting in a system that requires less than 14 Watts power dissipation. Data is integrated using Kalman filtering techniques reducing long term errors introduced by the Doppler and short-term errors introduced by the inertial sensors. The paper describes DIAS development and testing and contrasts the accuracies of the developed system versus the previously employed long-baseline approach. The integration of DIAS within the EODRWP and at-sea employment using the Cetus AUV completes the paper